The codons AAA, CCC, GGG, and UUU specify the amino acids lysine, proline, glycine, and phenylalanine, respectively. If the base sequence 5′-CCCAAATTTGGG-3′ is present in the coding strand of a stretch of DNA, what polypeptide sequence would be encoded by the corresponding template strand?

• A. lys-pro-gly-phe
• B. gly-phe-lys-pro
• C. phe-gly-pro-lys
• D. pro-lys-phe-gly

Answer: (D)

Verified step by step guidance

1. Understand that the coding strand of DNA is the strand that has the same sequence as the mRNA, except that thymine (T) in DNA is replaced by uracil (U) in RNA.
2. Identify the template strand, which is complementary to the coding strand. The template strand is used by RNA polymerase to synthesize mRNA.
3. Determine the complementary base pairs for the template strand from the coding strand. For the sequence 5′-CCCAAATTTGGG-3′, the template strand will be 3′-GGGTTTAAACCC-5′.
4. Transcribe the template strand into mRNA. Replace thymine (T) with uracil (U) in the mRNA sequence. The mRNA sequence will be 5′-CCCAAAGGGUUU-3′.
5. Translate the mRNA sequence into a polypeptide sequence using the codon table. The mRNA codons CCC, AAA, GGG, and UUU correspond to the amino acids proline, lysine, glycine, and phenylalanine, respectively, resulting in the polypeptide sequence pro-lys-phe-gly.